Component with inlay for damping vibrations

ABSTRACT

An exemplary embodiment includes an automotive brake component, such as a brake drum or a brake rotor, and an inlay coupled to the automotive brake component. The inlay constituting at least a portion of a braking surface that is acted upon during a braking event. The inlay damping vibrations in the automotive brake component when the component is vibrated.

TECHNICAL FIELD

The technical field generally relates to components such as drum brakeassemblies, and the construction and structure of drums for drum brakeassemblies.

BACKGROUND

Automobiles commonly have brake components such as drum brake assemblieson their rear wheels to help slow or stop the automobile. A drum brakeassembly includes a drum that is mounted to and rotates with a wheel andthat generates friction with a braking component, such as a brake pad,during a braking event to slow or stop the automobile. Drums aretypically made of steel or cast-iron, and can become worn over time, orcan vibrate.

SUMMARY OF EXEMPLARY EMBODIMENTS OF THE INVENTION

One exemplary embodiment includes a product which may include a drum andone or more inlays. The drum is used in a drum brake assembly, and mayhave a web portion and a hoop portion extending therefrom. The one ormore inlays may be located at the hoop portion and, during a brakingevent, may constitute at least a portion of a braking surface that comesinto contact with a braking component such as a brake pad. The one ormore inlays may help damp the vibrations in the drum when the drum isvibrated during use.

Another exemplary embodiment includes a product which may include a drumand one or more inlays. The drum is used in a drum brake assembly, andmay be made of a first material and may have a hoop portion. The one ormore inlays may be located at the hoop portion and may be made of asecond material that is different than the first material. In use, theone or more inlays may constitute at least a majority of a brakingsurface that comes into contact with a braking component such as a brakepad. Also, relative movement between the drum and the one or more inlaysmay help damp vibrations in the drum when the drum is vibrated, such asduring a braking event.

Another exemplary embodiment includes a method of making a product. Themethod may include placing an inlay in a mold cavity. The method mayalso include positioning the inlay to one side of the mold cavity sothat, when the product is finished, the inlay may constitute an exposedbraking surface that comes into contact with a braking component such asa brake pad during use. The method may further include filling the moldcavity with a molten material that, when solidified, is a drum used in adrum brake assembly. The drum may have a web portion and a hoop portionextending from the web portion, and the inlay may be located at the hoopportion.

Another exemplary embodiment includes a product which may include anautomotive brake component and an inlay. The inlay may be coupled to theautomotive brake component. The inlay may constitute at least a portionof a braking surface that is acted upon during a braking event. Theinlay may help damp vibrations in the automotive brake component whenthe automotive brake component is vibrated.

Other exemplary embodiments of the invention will become apparent fromthe detailed description provided hereinafter. It should be understoodthat the detailed description and specific examples, while disclosingexemplary embodiments of the invention, are intended for purposes ofillustration only and are not intended to limit the scope of theinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments of the invention will become more fully understoodfrom the detailed description and the accompanying drawings, wherein:

FIG. 1 is a perspective view of one embodiment of a drum having aninlay.

FIG. 2 is a cross-sectional view of the drum of FIG. 1.

FIG. 3 is a perspective view of another embodiment of a brake drumhaving a plurality of inlays.

FIG. 4 a is a fragmented cross-sectional view taken from a side of oneembodiment of an inlay.

FIG. 4 b is a fragmented cross-sectional view taken from a top ofanother embodiment of an inlay.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

The following description of the embodiment(s) is merely exemplary(illustrative) in nature and is in no way intended to limit theinvention, its application, or uses.

The figures illustrate several exemplary embodiments of a drum 10 thatis part of a drum brake assembly for an automobile. The drum 10 mayinclude one or more inlays 12 that may, among other things, help damp orotherwise dissipate vibrations in the drum, give better wear-resistanceto the drum, reduce the weight of the drum, and speed up themanufacturing process of the drum. As shown, the drum 10 has a generallycylindrical shape which naturally defines a number of directions withrespect to that shape. In this regard, the term “axially” as used hereindescribes a direction that generally corresponds to an imaginary centeraxis A (FIG. 2), and the term “circumferentially” as used hereindescribes a direction that generally corresponds to an imaginarycircumference about the center axis A.

Though described in the context of the brake drum assembly, the inlay 12may be used in other applications including, but not limited to,automotive components such as brake rotors, electric motors,transmission housings, gear housings, exhaust manifolds, cylindricalheads, brackets, and other components that are subject to vibrationsduring use. In the brake rotor example, the inlay 12 may be coupled to acheek portion thereof in order to constitute an exposed braking surfaceof the cheek portion. The term “automotive brake component” includescomponents of an automotive braking system such as the drum 10 and thebrake rotor.

The drum 10 may be mounted to an axle and may generate friction with abraking component such as a brake pad 13 (shown in phantom) when thebrake pad is pressed against it during a braking event. The drum 10 maybe made of a cast-iron, a steel, a ceramic, a polymer composite, analuminum, or any other suitable material known by skilled artisans.Referring to FIGS. 1 and 2, the drum 10 may include a web portion 14 anda hoop portion 16 extending from the web portion. The web portion 14 mayhave an axle hole 18 and a plurality of bolt holes 20, both of whichhelp mount the drum 10 onto the axle. The hoop portion 16 has an openend 21 and a labyrinth section 22 that is constructed to mate with acomplementary structure of another component of the drum brake assembly.An inner surface 24 of the hoop portion 16 extends circumferentiallyaround the hoop portion and axially therealong from the web portion 14and to the open end 21.

The inlay 12 may be coupled to the inner surface 24 of the hoop portion16 to help damp vibrations in the drum 10 and consequently help suppresssound and noise (e.g., ringing) emitted when the drum is vibrated. Forexample, relative sliding, movement, or other contact at an interfaceboundary formed between the hoop portion 16 and the inlay 12 generatesfriction therebetween which absorbs energy such as vibrations—so-calledCoulomb damping. The interface boundary may be formed along the innersurface 24 of the hoop portion 16 (or the component body) and anopposing surface of the inlay 12 (e.g., mechanically distinguishablesurfaces) that are in contact with each other but so that relativemovement at the interface boundary generates friction and dissipatesenergy so as to reduce vibrations. As used herein, the term “inlay” doesnot necessarily require that the component is inserted into the drum 10,rather the component may be merely coupled to the drum.

In select embodiments, the inlay 12 may be made of a number of materialsincluding, but not limited to, mild steel such as AISI 1010 steel andAISI 1008 steel, aluminum steel composites, stainless steel, titanium,various manganese alloys, metal matrix composites, or magnesium; thematerial may be a metal having a higher melting point than the materialof the web portion 14 and the hoop portion 16. Some of the examplematerials listed above may be lighter in weight, and may be morewear-resistant than the material of the web portion 14 and the hoopportion 16. In these instances, use of the inlay 12 reduces the overallweight of the drum 10 because the inlay replaces what would otherwise bethe material of the drum. Also, the drum may have a longer effectivelife.

In the exemplary embodiment of FIGS. 1 and 2, the inlay 12 may be aone-piece structure that is placed over the inner surface 24. The inlay12 may be coextensive with the circumference of the inner surface 24 andmay be coextensive with the axial length of the inner surface; in anembodiment not shown, the inlay 12 may not necessarily be coextensivewith the axial length of the inner surface. The inlay 12 may have afirst end 26 that is located near the open end 21, and may have a secondend 28 that is located near the web portion 14. The inlay 12 may alsohave an outer surface 30 that is exposed to and faces the brake pad 13,and has an inner surface 32 that faces the inner surface 24 of the hoopportion 16. In this embodiment, the outer surface 30 constitutes abraking surface 34. The braking surface 34 is that surface which comesinto contact with the brake pad 13 during a braking event. Friction isgenerated between the braking surface 34 and the brake pad 13 whichslows or stops the automobile. In this embodiment, the outer surface 30constitutes a majority of, and indeed, the entire braking surface 34such that contact will be made only between the brake pad 13 and theinlay 12, and not between the brake pad and the hoop portion 16. In somecases, having the inlay 12 as the braking surface 34 may enhancevibration damping characteristics because the inlay directly contactsthe brake pad 13 and thus sliding, movement, and/or other contact at theinterface boundary is more intense than it might otherwise be if theinlay were not the braking surface. The more intense contact may absorbmore vibrations.

In one example assembly process, the inlay 12 is press-fit into apre-cast hoop portion 16 in order to couple the two together. The inlay12 may be made by a separate and distinct manufacturing process, and theweb and hoop portions 14, 16 may be made by a separate and distinctcasting process. The outer diameter of the inlay 12 may be dimensionedslightly smaller than the inner diameter of the hoop portion 16 suchthat the inlay can be force-fit into the hoop portion when the two arebrought together coaxially. The inner diameter of the hoop portion 16may be a result of casting dimensions or may be the result of machining.Referring to FIG. 4 b, the inlay 12 may have a first attachment featuresuch as a plurality of ribs, one or more axial beads, or one or moreaxial splines 36 on its inner surface 32, and the hoop portion 16 mayhave a complementary second attachment feature such as recesses 38 onits inner surface 24 to help couple the inlay to the hoop portion. Inthis example, the first attachment feature is a projection thatinterfits with the second attachment feature to form a mechanical bondor coupling.

In another example assembly process, the inlay 12 is coupled to the hoopportion 16 by a cast-in-place process. The pre-formed inlay 12 may beplaced in a mold cavity, and then may be manually or automaticallypositioned in the mold cavity such that, when completed, the inlay isthe exposed braking surface 34. The mold cavity may then be filled witha molten material of the material used for the web and hoop portions 14and 16. Injecting the molten material into the mold cavity is but oneway of filling the mold cavity. Referring to FIG. 4 a, in this process,the first attachment feature of the inlay 12 may be a singlecircumferential projection, such as a tab 40, a plurality ofspaced-apart individual tabs, or the like. The tab 40 can extend fromthe first end 26, the second end 28, anywhere therebetween, or anycombination thereof. The second attachment feature of the hoop portionmay be a single complementary circumferential recess 42, a plurality ofcomplementary spaced-apart individual recesses, or the like. Indeed, thefirst attachment feature may be the recess or recesses, while the secondattachment feature may be the projection or projections. In any of theseexamples, one of the attachment features may be formed during thecast-in-place process. When the first attachment feature is aprojection, the molten material solidifies over the projection to formthe complementary recess. The resulting first and second attachmentfeatures thus interfit to form a mechanical bond or coupling thatsecures the inlay 12 and the hoop portion 16 together.

In yet another assembly process, the inlay 12 is coupled to the hoopportion 16 by a friction weld process. This may be performed in additionto the press-fit process. Once placed over the inner surface 24, afriction weld may be formed at an interface between the inner surface ofthe hoop portion 16 and the inner surface 32 of the inlay 12. Thefriction weld may only be formed at a portion of the interface, such asnear the first end 26, so as to avoid adversely affecting vibrationdamping attributes therebetween by reducing relative sliding, forexample. The friction weld may also be a number of separate frictionwelds that are spaced-apart with respect to each other.

As mentioned, using the inlay 12 as part of the drum 10 may help speedup the overall manufacturing process. For example, in a drum without theinlay 12, the inner surface 24 may have to be machined before use in anautomobile. Because the inlay 12 is located over the inner surface 24,the inner surface need not be machined to such an extent, or at all.

In some embodiments, the inner surface 32 of the inlay 12 may be bondedto the inner surface 24 of the hoop portion 16 by adhesive bonding orany other suitable process. And in some embodiments, the projections maybe similarly bonded to the recesses.

In some embodiments, the inner surface 32 or the inner surface 24 may becoated to form a layer that facilitates energy absorption between theinlay 12 and the hoop portion 16, and thus helps damp vibrations.Suitable coatings may include a plurality of particles which may bebonded to each other and/or to the particular surface by an inorganicbinder, an organic binder, or another suitable bonding material.Suitable binders may include epoxy resins, phosphoric acid bindingagents, calcium aluminates, sodium silicates, wood flour, or clays. Inone embodiment, the coating may be deposited on the particular surfaceas a liquid dispersed mixture of alumina-silicate-based, organicallybonded refractory mix. In other embodiments, the coating may include atleast one of alumina or silica particles, mixed with a lignosulfonatebinder, cristobalite (SiO₂), quartz, or calcium lignosulfonate. Thecalcium lignosulfonate may serve as a binder. In one embodiment, thecoating may include any types of coating used in coating casting ladlesor vessels, such as Ironkote or Ladlekote type coatings. In oneembodiment, a liquid coating may be deposited on a portion of theparticular surface, and may include high temperature Ladlekote 310B. Inanother embodiment, the coating may include at least one of clay, Al₂O₃,SiO₂, a graphite and clay mixture, silicon carbide, silicon nitride,cordierite (magnesium-iron-aluminum silicate), mullite (aluminumsilicate), zirconia (zirconium oxide), or phyllosilicates. In oneembodiment, the coating may comprise a fiber such as ceramic or mineralfibers.

Interface boundaries that may absorb energy and thus help dampvibrations may be formed with the coatings and may include, but is notlimited to: the inner surface 24 of the hoop portion 16 against thelayer formed, the inner surface 32 of the inlay 12 against the layer,the inner surface 24 against the particles or fibers, the inner surface32 against the particles or fibers, and movement of the particles orfibers against each other.

The exact thickness of the coating may vary and may be dictated by,among other things, the materials used for the inlay 12 and for the hoopportion 16, and the desired degree of vibration damping. Examples ofthicknesses may range from about 1μ-400 μm, 10 μm-400 μm, 30 μm-300 μm,30 μm-40 μm, 40 μm-100 μm, 100 μm-120 μm, 120 μm-200 μm, 200 μm-300 μm,200 μm-550 μm, or variations of these ranges.

Some examples of suitable particles or fibers that may be a part of aparticular coating may include, but is not limited to, silica, alumina,graphite with clay, silicon carbide, silicon nitride, cordierite(magnesium-iron-aluminum silicate), mullite (aluminum silicate),zirconia (zirconium oxide), phyllosilicates, or otherhigh-temperature-resistant particles. In one example, the particles mayhave a length as defined by the longest dimension in a range of about 1μm-350 μm, or 10 μm-250 μm.

In an embodiment having a coating with particles, fibers, or both, theparticles may have an irregular shape (e.g., not smooth) to augmentvibration damping. The particles, fibers, or both, may be bonded to eachother, to the inner surface 24 of the hoop portion 16, to the innersurface 32 of the inlay 12, or to both, because of, among other thins,the inherent bonding properties of the particles or fibers. For example,the bonding properties of the particles or fibers may be such that theparticles or fibers may bind to each other or to the inner surface 24,to the inner surface 32, or to both under compression. In an example,the particles, fibers, or both, may be treated to provide a coating onthe particles or fibers themselves, or to provide functional groupsattached thereto to bind the particles together or attach the particlesto at least one of the inner surface 24 or the inner surface 32. Inanother example, the particles, fibers, or both may be embedded in atleast one of the inner surface 24 or the inner surface 32 to augmentvibration damping.

In another embodiment, the particles, the fibers, or both, may betemporarily held together, held to the inner surface 32, the innersurface 24, or held to both, by a fully or partially sacrificialcoating. The sacrificial coating may be consumed by molten metal orburnt off when metal is cast around or over the inlay 12. The particles,fibers, or both are left behind and trapped between the hoop portion 16and the inlay 12 to provide a layer consisting of the particles, thefibers, or both.

In another embodiment, one or more of the inner surface 24 and the innersurface 32 may include a relatively rough surface including a pluralityof peaks and valleys to enhance the frictional damping of the part. Inthis example, the inner surface 24, the inner surface 32, or both, maybe abraded by sandblasting, glass bead blasting, water jet blasting,chemical etching, machining, or any other suitable process that mayproduce relatively rough surfaces.

In an embodiment where the inlay 12 is cast-in-place, the particles,fibers, or both may be exposed to the temperature of a molten material,and the inlay 12, the particles, the fibers, or all, may be made frommaterials that can resist flow and significant erosion during thecasting process. For example, the inlay 12, the particles, the fibers,or all, may be composed of refractory materials that can resist flow anderosion at temperatures above 1100° F., above 2400° F., or above 2700°F. In an example casting process, when molten material is poured, theinlay 12, the particles, the fibers, or all, should not be wet by themolten material so that the molten material does not bond where aninterface boundary would otherwise be formed.

In an embodiment where the drum 10 is made using a process that subjectsthe inlay 12, the particles, the fibers, or all, to relatively hightemperatures associated with molten materials, the inlay 12, theparticles, the fibers, or all, may be made from a variety of materialsincluding, but not limited to, non-refractory polymeric materials,ceramics, composites, wood, or other materials suitable for frictionaldamping.

In another embodiment, a wettable surface may be provided that does notinclude a layer with particles or fibers, or a wettable material such asgraphite is provided over a section of the inlay 12, so that the castmetal is bonded to the wettable surface in order to attach the inlay tothe hoop portion 16 while still permitting frictional damping on thenon-bonded surfaces.

Another exemplary embodiment of a drum 110 is shown in FIG. 3. Thisembodiment is similar in some ways to that described in FIGS. 1 and 2.One difference is a plurality of individual and distinct inlays 112. Theinlays 112 may be spaced at a distance apart from each other and may bespaced circumferentially around a hoop portion 116. The inlays 112 maybe inset into the hoop portion 116 such that an inner surface 124 of thehoop portion is flush with an outer surface 130 of each of the inlays.Thus, a braking surface 134 may include both the inner surface 124 andthe outer surface 130 as a brake pad may come into contact with bothduring a braking event. In other embodiments, the inlays 112 need notnecessarily be spaced apart at equal distances as shown, and there canbe more or less of them than shown. Still in this embodiment, the outersurfaces 130 of the inlays 112 may constitute a majority of the exposedbraking surface 134, though need not.

The above description of embodiments of the invention is merelyexemplary in nature and, thus, variations thereof are not to be regardedas a departure from the spirit and scope of the invention.

1. A product comprising: a drum for a drum brake assembly, the drumhaving a web portion and a hoop portion extending from the web portion;and at least one inlay located at the hoop portion and constituting atleast a portion of a braking surface contacting a braking component, theinlay damping vibrations in the drum when the drum is vibrated.
 2. Aproduct as set forth in claim 1 wherein the drum comprises a firstmaterial and the inlay comprises a second material that is differentthan the first material.
 3. A product as set forth in claim 1 whereinthe inlay is a single inlay circumferentially coextensive with the hoopportion, lying on a surface of the hoop portion, and constituting theentire braking surface contacting the braking component.
 4. A product asset forth in claim 1 wherein the inlay includes a plurality ofindividual inlays circumferentially spaced around the hoop portion andeach being inset in the hoop portion flush with a surface of the hoopportion so that the inlays and the surface constitute the brakingsurface contacting the braking component.
 5. A product as set forth inclaim 1 wherein relative movement at an interface formed between thedrum and the inlay damps vibrations in the drum when the drum isvibrated.
 6. A product as set forth in claim 1 wherein the drum has afirst attachment feature and the inlay has a complementary secondattachment feature interfitting with the first attachment feature tocouple the inlay to the drum.
 7. A product as set forth in claim 6wherein the first attachment feature is a recess and the secondattachment feature is a projection sized to fit within the recess.
 8. Aproduct as set forth in claim 6 wherein the first and second attachmentfeatures are at least one friction weld formed at an interface of thedrum and the inlay.
 9. A product as set forth in claim 1 wherein theinlay is formed with the drum by a cast-in-place process.
 10. A productas set forth in claim 1 wherein the inlay is placed in the drum by apress-fit process.
 11. A product comprising: a drum for a drum brakeassembly, the drum comprising a first material and having a hoopportion; and at least one inlay located at the hoop portion andcomprising a second material that is different than the first material,the inlay constituting at least a majority of an exposed braking surfacecontacting a braking component, wherein relative movement between thedrum and the inlay damps vibrations in the drum when the drum isvibrated.
 12. A product as set forth in claim 11 wherein the inlay is asingle inlay circumferentially coextensive with the hoop portion, lyingon a surface of the hoop portion, and constituting the entire brakingsurface contacting the braking component.
 13. A product as set forth inclaim 11 wherein the inlay includes a plurality of individual inlayscircumferentially spaced around the hoop portion and each being inset inthe hoop portion flush with a surface of the hoop portion so that theinlays and the surface constitute the braking surface contacting thebraking component.
 14. A product as set forth in claim 11 wherein thedrum has a first attachment feature and the inlay has a complementarysecond attachment feature interfitting with the first attachment featureto couple the inlay to the drum.
 15. A product as set forth in claim 10wherein the inlay is formed with the drum by a cast-in-place process.16. A product as set forth in claim 10 wherein the inlay is placed inthe drum by a press-fit process.
 17. A method of making a product, themethod comprising: placing an inlay in a mold cavity; positioning theinlay in the mold cavity so that, when finished, the inlay constitutesan exposed braking surface that during a braking event contacts abraking component; and filling the mold cavity with a molten materialthat, when solidified, will make a drum for a drum brake assembly, thedrum having a web portion and a hoop portion extending from the webportion, the inlay being located at the hoop portion.
 18. The method asset forth in claim 17 further comprising: providing a first attachmentfeature on the inlay; and forming a second attachment feature of thedrum by the molten material solidifying with the first attachmentfeature so that the inlay and the drum are coupled together.
 19. Aproduct comprising: an automotive brake component; and an inlay coupledto the automotive brake component and constituting at least a portion ofa braking surface being acted upon during a braking event, the inlaydamping vibrations in the automotive brake component when the automotivebrake component is vibrated.